The present invention relates generally to curtains or closures for covering the open ends of cargo containers, luggage trailers, and trucks, and, more particularly, to a unitary fabric and webbing closure that functions both as a cut-resistant cargo curtain and a load retainer.
Cargo containers of many forms have been used for transporting land, sea, and air cargo for many years. One type of cargo container is box-like, with at least two side walls, a top, and a flat bottom. Typically, one end of the cargo container is open for loading and unloading cargo. Various door closures can be used for opening and closing the open ends of such containers. One type of closure has been a rigid door closure which covers the opening to reduce tampering, to prevent the loss of small items, and to prevent the cargo from being exposed to dirt, moisture, and ultraviolet light.
Another type of closures include the combination of a webbing and a fabric closure. This type of closure is generally preferred over rigid door closures because it tends to be much lighter and less expensive. The fabric covers have typically been formed from canvas, or vinyl coated nylon or polyester. However, each of these fabrics lacks the durability to withstand physical stresses or lacks resistance to environmental conditions or harsh chemicals common to the transportation industry. For example, exposure to ultraviolet light, diesel and jet fuels, and oils, tends to rapidly degrade such fabric covers. Accordingly, the durability of a cargo cover is ultimately determined by its tear-strength, abrasion resistance, cut-and-stab resistance and ability to withstand environmental and chemical exposure. Otherwise, the product life is very limited and replacement costs are high. Because fabric covers lack the durability to also serve as load retainers, a separate webbing or netting is required to keep the cargo restrained so that it cannot pass through the covered end or fall out.
There is known in the art a cargo curtain in the form of a woven fabric wherein the yarns of the fabric are constructed of long-chain extended (ultra-high molecular weight) polyethylene fibers. Curtains formed from this woven fabric have exhibited increased strength and durability, and are considerably lighter than fabrics previously available. As a result, transportation expenses and replacement costs have been reduced. However, the sheer mass and bulk of cargo stowed in cargo containers still often require that additional measures be taken to secure cargo within the containers so that small articles are not lost and so that large and small articles do not penetrate the cargo curtains. Again, restraining such loads has heretofore been achieved by applying a combination of covers and webbing or nets, thereby increasing the weight, labor requirements, and required parts inventory, while also increasing total transportation costs. Further, by their very design, webbing and nets are subject to entanglement and must be either tediously untangled, or frequently must be cut away, rendering them subsequently unserviceable.
The present invention is directed to a unitary closure for covering the openings of cargo containers, baggage trailers, or trucks that accomplishes both of the above-described functions. Thus, the closure described hereinafter functions as both a cut-resistant cargo curtain and a load retainer for preventing cargo from falling out of the cargo container or otherwise penetrating the closure. Further, the closure described herein may be installed or removed in a fraction of the time required to install separate covers and nets or webbing and is not subject to the entanglement problems inherent in the prior art.
Accordingly, one aspect of the present invention is to provide a unitary cut resistant fabric curtain and load retainer for enclosing the open ends of cargo containers having side walls, a top wall, and a bottom wall. As used here, cargo containers include uniform load devices (ULDs), air cargo containers, baggage trailers, sea-land containers, over-land trailers, and the like.
The unitary fabric curtain and load retainer includes at least one panel of fabric formed of at least one layer of fabric woven with yarns formed from fibers sufficiently cut and tear resistant to prevent cargo from penetrating the curtain. The fabric is desirably also resistant to heat, cold, ultraviolet (UV) radiation, and chemicals such as diesel and jet fuels and oils. Two such yarns formed from long chain polyethylene fibers are available from Honeywell under the trademark SPECTRA(copyright) or from DSM under the trademark DYNEEMA(copyright) However, any other suitable high-strength yarns having the characteristics described above may be used. The term xe2x80x9chigh strength yarnsxe2x80x9d means yarns formed from fibers having a tenacity exceeding 20 grams/denier, and desirably exceeding 30 grams/denier. The fabric may further be uncoated, coated, or laminated with a thermoplastic film.
The fabric closure is formed so that it substantially covers the open end of the cargo container. Preferably, at least some portion overlaps the peripheral edges of the cargo container side walls and top. The overlap portion provides an additional barrier to environmental or other anticipated undesirable elements, and this barrier may be further enhanced by securing the overlap portion around the periphery of the cargo container with a cable or the like that is inserted through a hem formed in the edge of the overlap portion and fastened to the lower front corners of the container.
Once the fabric closure has been secured around the periphery of the cargo container, it must be drawn taut to restrain cargo stowed in the container. One way of tensioning the fabric panel is by means of web straps and fasteners that are attached around at least part of the periphery of the fabric closure. For example, it may be desirable to attach the fabric cover along one side and along either the top or bottom of the cargo container with hooks that are attached to the outer edges of the fabric. Adjustable fasteners attached along the opposite side and top or bottom of the fabric closure may then serve the dual function of attaching the fabric closure to those sides of the cargo container as well as drawing the fabric taut, thereby restraining cargo stowed in the cargo container, while preventing items of cargo from slipping around or through the fabric closure. Preferably, the fabric closure is constructed so that opposed pairs of web straps are attached around the periphery of the fabric panel. The term xe2x80x9copposed pairxe2x80x9d means that each strap of a pair is positioned at a point on the opposite side of the panel from the other so that the pair form a xe2x80x9cload pathxe2x80x9d. The straps are located to correspond with fasteners attached to the cargo container around the open end thereof. Again, each pair should include one member that is adjustable so that the cover can be made taut. When the strap pairs are attached co-linearly to a high-strength fabric panel such as that described herein, the straps and fabric combination provide load restraint at least equivalent to separately formed webbing or nets. The straps are formed of nylon, but any suitable high strength webbing material may be used. The term xe2x80x9chigh strength webbingxe2x80x9d material means webbing having a tear strength of about 900 pounds or more per linear inch of webbing width. Desirably the straps are sewn to the fabric panel with a high strength thread such as SPECTRA(copyright) or DYNEEMA(copyright). The web straps are secured to fasteners, such as hooks and buckles, for securing the top and opposed bottom portions of the fabric panel to the cargo container.
Access to the entire open end of a cargo container is obtained by simply loosening and removing some or all of the straps and fasteners from the cargo container. However, for limited access, such as for inspection, the adjustable fasteners on at least one side of the closure may be loosened so that a side portion of the closure may be folded back.
Alternatively, the closure may be constructed from two panels or from a single panel having an opening formed substantially along its length or width. Where such an opening is formed across the panel, additional fasteners are provided to appropriately close the opening for transit.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.